Prep for initial stable release

[nwalters512]

This contains my work toward an initial v1.0.0 release. I think the API is stable enough that we can finally move this out of alpha. I'm going to release these changes as v1.0.0-beta.1 and start using it in a production app for a few weeks. If everything still looks good, I'll promote things to v1.0.0!

Changes

• Fix NextJS HMR functionality breaks #27; HMR should now work properly 🎉 The root cause was that we were never rendering a new component if the key didn't change. To resolve this, I've made the key prop required. When deciding how to update when the children change, we check if the key didn't change. If the key didn't change but the component itself did, we'll re-render it immediately without animating the transition. Otherwise, we'll proceed as we did before.
• Update all dev dependencies.
• Update all dependencies in the examples.
• Add next-page-transitions as a dependency to the examples; fixes the problem initially described in Examples depend on next-page-transitions module but it isn't listed in package.json as a dependency #22
• Switch to a different way of identifying if timeoutsShape is defined; see Error when running on production env #17 for initial bug.